Hi Walt, There are some options to georeference a vector layer:
Since it is 2D, you can georeference it to a projected coordinate system with ogr2ogr command line application, in the same way that a raster layer can be georeferenced from control points. You can use any transformation method and differences will be compensated if the number of control points provided is higher than the minimum requirement for that method. Vector Bender plugin can georeference the layer in QGIS, but if you define more control points than strictly necessary the transformation will not be linear also not compensated, but triangulated into as many linear transformations as control points more than three. If you have the coordinates in both systems (the local cartesian of the original drawing and the geographic but projected one) you can align the drawing in AutoCAD and export to dxf, import in QGIS and just assign the proper CRS. Also you can translate, rotate and scale in QGIS with geoprocessing algorithms or with QAD plugin. If you need to georeference to geographic coordinates instead of a projected system, you can use a linear but 3D transformation to geocentric and then a conversion to geographic. It's probably not what you want to do. But you also shouldn't use a 2D linear transformation to go from the drawing system to a geographic one. Regards, Gabriel. On Wed, Feb 3, 2021 at 4:13 PM Walt Ludwick <w...@valedalama.net> wrote: > I've received a 3D AutoCAD file from an architect that i managed to > convert into 2D .dxf format and import into my QGIS project, but it is > out-of-scale and out-of-place, so i guess i need to add some georeferencing > coordinates to the file. > > This should be easy enough, since it's an accurate representation of a > building that's already in the project -with an additional wing tacked on- > so i'm thinking i could just use a few corners of that existing buildings > as ground control points, and map them to the corresponding corners on this > .dxf model, then maybe all other co-ordinates could be automatically > generated by some tool, if i could just find the right one for the job. > > Is there in fact any such easy way to do this thing? > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user >
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